The present invention relates to an automatic document feeder (ADF) which may be mounted on the top of a copier, laser printer or similar image recorder for transporting ordinary sheet documents or a computer form (CF) document, as desired. More particularly, the present invention is concerned with an ADF capable of controlling the transport of a CF document.
An ADF is extensively used today with an image recorder for automatically transporting a document to be recorded to a recording position of the recorder, thereby remarkably increasing the recording speed available with the image recorder. An advanced ADF is capable of handling a so-called CF document or paper in addition to ordinary documents in the form of sheets. The CF document has a plurality of consecutive pages thereon which adjoin each other with the intermediary of a perforation and are stored in a folded position. This type of ADF transports such a CF document to a predetermined recording position, sets it there, and then drives it out from the ADF via an outlet. When mounted on the top of the image recorder, this ADF allows the successive pages of the CF document to be recorded one after another.
Before the ADF capable of handling a CF document is operated to record successive images printed on a CF paper continuously, a collecting box, for example, is placed beneath the outlet of the ADF for receiving the CF document. On the turn-on of a predetermined key, a continuous copying operation is started. As soon as the first page of the CF document is driven out via the outlet to reach the collecting box, the operator determines the direction in which the document should be folded along the perforation intervening between the first and second pages of the document. Specifically, the CF document is set on the bottom of the box with the first page thereof folded in an expected or easy-to-fold direction. As a result, the second and successive pages of the CF paper sequentially arriving at the box are automatically neatly turned down in the box one after another.
However, when the determined direction for folding the CF between the first and second pages is not correct, the first page is not accurately set on the bottom of the box and the first page is often folded in the other direction or folded only loosely. Then, the second and successive pages each is folded in the wrong direction and not neatly folded with the result that they pile up to more than an expected height. In the worst case, such CF paper will overflow the box. While the CF paper so folded in wrong directions may be refolded in right directions afterwards, refolding it after many pages have overflown the box is time-consuming since the CF paper has a substantial length.
In parallel with the trend toward a higher recording speed, e.g., higher copying speed, the speed at which a scanner is moved in a reciprocating motion relative to a platen is decreasing. When a CF document is used, the scanning speed cannot be increased unless the time per page during which the document stays on the platen is reduced. Therefore, the transpot speed per page (reciprocal of the interval between the start of transport of one page of document and the discharge of the same to the outside) is high. It follows that the operator has to determine the direction in which the CF document being discharged is easier to fold along the perforation intervening between the first and second pages within an extremely short period of time. Specifically, the operator usually folds the CF document in opposite directions along the perforation to see the direction in which the document folds more easily or neatly, and again folds it in such a direction. This, however, has a problem that when the operator determines the direction in which the CF paper is easier to fold after folding it twice, the operator has to fold it again in the easier direction, i.e., three times of folding is necessary in total. When the operator has determined the folding direction, several pages of the CF paper have already been driven out. Then, the operator sequentially correctes the folds of the second and successive pages in direction. However, manually refolding the second and successive pages one by one cannot keep up with the rapid discharge of the CF document.